The present invention relates to a signal display element for the display of more than two informations by electromagnetically excited magnetic tilting plates; the signal display element has a base plate, on the base plate there are the tilting plates provided with a part containing the magnets and the tilting plates are supported in bearings on the baseplate and can be displaced in relation to each other in direction of the axis of rotation; magnetic axes of the parts of the tilting plates containing the magnets are preferably normal to the plane of the tilting plates, furthermore, bipolarly excitable field coils are associated with the tilting plates for the control thereof.
As it is well known, signal display elements used to be applied for displaying numbers, signals and symbols, such as according to Hungarian Pat. No. HU-PS 157 250, they are provided with plates having a magnetic part, to be tilted by electromagnetic control and in such a manner that as a consequence of the tilting motion one face or the other of the plates becomes visible. The plates can be tilted around a lateral edge or an edge being parallel with the lateral edge; the two surfaces of the tilting plates are carrying different informations, for example, they are differently colored, while the part of the baseplate which became visible, is carrying an identical information, e.g. it has the same color, as the surface of the tilting plate which became visible. The tilting plates are made, at least partly, of a permanent magnetic material, the magnetic axis of which is advantageously normal to the plane of the tilting plates. In such a manner two different informations can be displayed with the signal display element.
Furthermore, an element based on the principle of the previously described signal display is known, which is suitable for displaying more than two informations, such a signal display element is specified in Hungarian Pat. No. HU-PS 158 828. In contrast to the earlier solution, with this solution the axes of rotation of the signal display elements are not fixedly supported in bearings, but can be moved in the inside of the U-shaped (hairpin) bearings, when guided, similarly to books resp. covers provided with filler sheets. With this solution a plurality of tilting plates can be arranged in an element and the number of the informations displayed, e.g. of the colors is larger by one, than the number of the tilting plates.
In both solutions thickness of the single tilting plates is determined by the necessary thickness (the necessary magnetic energy content) of the magnets arranged in the tilting plates having a magnetic axis preferably perpendicular to the plane of the tilting plates. Accordingly, with the latter solution containing a plurality of tilting plates, a field coil generating a very strong magnetic field is required on the control side, because, if all the tilting plates are bearing up against each other on one side, the magnetic part of the topmost tilting plate will lie in a significant distance from the magnetic coil exciting it. Furthermore, an increase of the total thickness of the plates will push apart the displaying surface of the adjacent dots in depth, and as a consequence, when viewed at a larger angle of sight, this can be disturbing from the optical viewpoint.